The invention generally relates to combination gas venting and anti-reflux devices and more specifically relates to such devices when used in urinary drainage bags.
Urinary drainage bags are commonly made from two flat sheets of flexible plastic sealed together at their edges. Typically, urinary drainage bags have a potential capacity of approximately 2,000 ml. Depending on the shape of the two flat sheets, it may be necessary to allow air into the bag as the bag begins to fill with liquid, to assist in the separation of the two sheets comprising the bag. During use of the bag, an undesirably high positive pressure can develop in the bag after the bag has expanded to its maximum potential volume. If this positive pressure exceeds the static pressure of a patient's bladder (which is approximately 10 cc. water head height), the flow of urine out of the bladder and into the bag can be impeded or stopped. Therefore, it is commonly desired to provide a means of venting gas from the inside of the urinary drainage bag to the atmosphere to prevent such undesirably high pressure from occurring in the bag.
Another feature common to urinary drainage systems is to provide an anti-reflux or one-way valve either at an inlet to the urinary drainage bag or in a drainage tube between a patient and the bag. The function of this valve is to prohibit urine in the bag from flowing back into the bladder if the bag is inadvertently raised above the level of the patient's bladder. This is particularly important if infectious organisms are present, or if high dosages of antimicrobial materials that are potentially harmful to the bladder are in the bag.
A logical location for an anti-reflux valve is at the bag inlet port. Unfortunately if the anti-reflux valve is very effective, it is also an effective barrier so as to prevent gas from venting between the inside of the bag and any gas venting means that may be present in the drainage tube. Therefore, at least three critical and costly components are typically present in a urinary drainage bag. One component being an anti-reflux valve, a second component being a separate gas venting means for venting gas between the inside of the bag and the atmosphere, and a third component being a gas venting means between the drainage tube and the atmosphere. Thus, if a urinary drainage bag includes an anti-reflux valve, a single gas vent is typically not considered to be sufficient; two separate gas vents have been commonly used. One gas vent is used to vent gas in the drainage tube upstream of the anti-reflux valve, and a separate gas vent (typically located on a wall of the drainage bag) is used to vent gas in the bag downstream of the anti-reflux valve.
U.S. Pat. No. 4,334,537 to Peterson is representative of a typical three-component urinary drainage system having two separate vents as well as an anti-reflux valve. As can be seen in FIG. 1 of the Peterson patent, a connector 30 may be provided which contains vent 32 which can vent gas in a drainage tube to the atmosphere. The connector may also contain an anti-reflux mechanism as illustrated in FIG. 2. It should be noted, that a separate vent 20 is required in this type of system to vent any gas present in the drainage bag to the atmosphere.
U.S. Pat. No. 4,512,770 to Cianci et al., and U.S. Pat. No. 3,604,420 to Vaillancourt also describes similar arrangements.